The goal of this research is to uncover the stepwise process by which new morphological structures and the networks that control their development evolve. Each and every morphological structure evolved at some point in the past, and our understanding of the origins of the developmental networks that spatially orchestrate development is still a mystery. It is becoming increasingly appreciated that our understanding of these networks at the molecular level will lie at the heart of connecting genetic variation to differences in phenotype, including the predisposition to disease. By characterizing a recently evolved morphological novelty of Drosophila melanogaster, this project will provide a unique perspective on how networks arise and are altered to generate differences in three dimensional forms.